The use of thermophilic enzymes has revolutionized the field of recombinant DNA technology. Polymerases (DNA and RNA), ligases, exonucleases, reverse transcriptases, polynucleotide kinases and lysozymes, as well as many other thermophilic enzymes, are of great importance in the research industry today. In addition, thermophilic enzymes are also used in commercial settings (e.g., proteases and lipases used in washing powder, hydrolidic enzymes used in bleaching). Identification of new thermophilic enzymes will facilitate continued DNA research as well as assist in improving commercial enzyme-based products.
This invention pertains to a novel bacteriophage of Rhodothermus marinus, bacteriophage RM 378, which can be isolated from its native environment or can be recombinantly produced. The invention additionally pertains to the nucleic acids of the genome of bacteriophage RM 378 as deposited, as well as to the nucleic acids of a portion of the genome of bacteriophage RM 378 as shown in FIG. 1; to isolated nucleic acid molecules containing a nucleotide sequence of an open reading frame (or more than one open reading frame) of the genome of bacteriophage RM 378, such as an open reading frame as set forth in FIG. 2; to isolated nucleic acid molecules encoding a polypeptide obtainable from bacteriophage RM 378 or an active derivative or fragment of the polypeptide (e.g., a DNA polymerase, such as a DNA polymerase lacking exonuclease domains; a 3xe2x80x2-5xe2x80x2 exonuclease, such as a 3xe2x80x2-5xe2x80x2 exonuclease lacking DNA polymerase domain; a 5xe2x80x2-3xe2x80x2 exonuclease (RNase H); a DNA helicase; or an RNA ligase); to DNA constructs containing the isolated nucleic acid molecule operatively linked to a regulatory sequence; and also to host cells comprising the DNA constructs. The invention further pertains to isolated polypeptides encoded by these nucleic acids, as well as active derivatives or fragments of the polypeptides.
Because the host organism of the RM 378 bacteriophage is a thermophile, the enzymes and proteins of the RM 378 bacteriophage are expected to be significantly more thermostable than those of other (e.g., mesophilic) bacteriophages, such as the T4 bacteriophage of Escherichia coli. The enhanced stability of the enzymes and proteins of RM 378 bacteriophage allows their use under temperature conditions which would be prohibitive for other enzymes, thereby increasing the range of conditions which can be employed not only in DNA research but also in commercial settings.